habitual bipedal walking, nonhoning chewing, primate that walks upright, has opposable thumbs, and possesses a large brain; only living members are humans
consists of homo sapiens and our fossil ancestors, all bipedal hominids back to the divergence from african great apes
bipedal characteristics
(human) short, broad pelvis, valgus angle of femur, foramen magnum farther forward than in apes, "s" shaped vertebral column, changes in foot and leg, small canines, tool use, large brains
(ape) large canines, can walk upright, no tool use, small brain
darwins hunting hypothesis
hands used to make tools, tools used for hunting, quadrupedal->bipedal, large canines->small canines, no tool use->tool use, small brain->large brain
patchy forest hypothesis (rodman and mchenry)
walking in two feet may be more energetically efficient, forest fragmentation, bipedalism freed the hands to pick up food
provisioning hypothesis (lovejoy)
males provisioned mothers and their offspring, males freed their hands, selective advantages of monogamy
thermoregulation hypothesis (wheeler)
negative feedback, thermoreceptors to brain, temperature control center sends message to effectors
nonhoning chewing
blunt, non projecting canines, smaller canines, no diastema (most), wear on the tips of canines rather than on the back, cusps on P3 of equal size
sahelanthropus tchadensis
chad, 7 mya, small braincase (350 cc), vertical face - unusual, small canines - wear at tips, bipedal?, lived in forest near a lake
orrorin tugenesis
tugen hills kenya, 6 mya, canine wear at tips, two femurs, bipedality, curved phalanx, lived in forest
ardipithecus kadabba
5.8-5.6 mya, awash river valley ethipoia, intermediate honing complex, thin enamel, curved foot phalanges, bipedalism, lived in wooded setting
ardipithecus ramidus
4.4 mya, awash river valley ethipoia, small brain, no honing complex, thin enamel, curved foot phalanges, full bipedalism, lived in wooded etting